Axial fan

ABSTRACT

An axial fan comprises a base, a rotor mounted on the base by a shaft, and a plurality of blades mounted on the rotor. The blade comprises a passive part corresponding to a feeder and an active part, so that a main airflow from the feeder drives the passive part rotating around the shaft to synchronously rotate the active part, to increase flow rate of airflow, to decrease the pressure and to dissipate heat generated from a heat source.

BACKGROUND OF THE INVENTION

1. Field of Invention

The invention relates to a fan, and in particular to an axial fan that can rotate without a motor.

2. Related Art

A conventional fan is actuated by a single motor, expelling airflow to dissipate heat from a heat source. The fan, however, cannot function without a motor. The cost on the motor is inevitable and a space must be provided for the motor. If an electronic device requires several fans to dissipate heat thereof, more motors will be required and will increase power consumption of the electronic device.

SUMMARY OF THE INVENTION

An axial fan according to the present invention can be actuated by a main airflow from a feeder, so that the axial fan can be rotated without a motor, thus decreasing cost and reducing power consumption.

The axial fan includes a base, a rotor mounted on the base by a shaft, and a plurality of blades disposed around the rotor. The blade includes a passive part corresponding to a external feeding port, and an active part. The main airflow from the feeder drives the passive part, so that the blades can rotate around the shaft to synchronously drive the active part.

The passive part of the blade is near the rotor and the active part thereof is far from the rotor. The main airflow from the feeder is divided into a first airflow and a second airflow by the passive part of the blade, so that a pressure difference between the first and second airflows drives the passive part to rotate around the shaft. The passive part has a wing section.

When the active part of the blade rotates around the shaft, the pressure of airflow at the outlet is smaller than that at the inlet so that the airflow could be continuously impelled.

The shaft is coupled to the base by a bearing. The bearing is selected from the group consisting of a sleeve, a ball and a magnetic. The blade further includes a first partition disposed between the passive part and the active part. The first partition could be a circular ring surround the shaft or a hollow cylinder disposed on each blade.

The axial fan further includes a plurality of ribs and a housing. The ribs connect the housing and the base. The axial fan further includes a second partition disposed on the ribs. The second partition could be a circular ring or a hollow cylinder disposed on each rib.

The axial fan of the invention is a fan without needing a motor.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

FIG. 1 is a schematic diagram of an axial fan of one embodiment according to the present invention;

FIG. 2 is a schematic sectional view of the axial fan of one embodiment according to the present invention;

FIG. 3A is a schematic sectional view of a passive part of the axial fan of one embodiment according to the present invention;

FIG. 3B is a schematic diagram of an active part of the axial fan of one embodiment according to the present invention; and

FIG. 4 is a schematic sectional view of an axial fan of another embodiment according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 and 2 are schematic diagram and sectional view of an axial fan 1 of one embodiment according to the present invention. The axial fan 1 includes a base 10, a rotor 12, a shaft 13 disposed on the base 10, a plurality of blades 14 disposed around the rotor 12, a plurality of ribs 15, a housing 16, a bearing 100, an inlet 18 and an outlet 19. The base 10 is mounted on the housing 16 by at least one rib 15. The housing 16 defines the field of airflow. The rotor 12 is mounted on the base 10 by the shaft 13, so that the rotor 12 mounted on the blades 14 rotates around the shaft 13 with respect to the base 10 to dissipate heat from a heat source.

A main airflow provided from a feeder 2 blows the blades 14 to generate power. Each blade 14 includes a passive part 141 corresponding to a external feeding port 210 of the feeder 2 and an active part 142.

FIG. 3A is a sectional view of the passive part 141 along an arc direction thereof. When the main airflow passes through the passive part 141 along the direction of arrows a1 shown in FIG. 2, the main airflow is divided into a first airflow and a second airflow due to different paths at both sides of the passive part 141. The passive part 141 is preferably formed with a wing section, to form a pressure difference between the first and second airflows. It is to be understood that the pressure difference between the first and second airflows drives the passive part 141 to move along the direction of arrows “A” shown in FIG. 3A, according to Bernoulli's law, and thus the blades 14 are rotated around the shaft 13, i.e., the active parts 142 are synchronously rotated around the shaft 13.

FIG. 3B is a sectional view of the active parts 142 along an arc direction thereof. An arrow “B” shows the rotation direction of the active parts 142. Due to the active parts 142 having a section similar to a blade of a conventional fan, the pressure at the inlet 18 is lower than the pressure at the outlet 19 when the active parts 142 are rotated. Thus, the exterior air can be drawn into the axial fan 1 via the inlet 18 and expelled via the outlet 19 along the path of arrows b1 showed in FIG. 2, blowing on the heat sink or area to dissipate heat. Preferably, the passive part 141 of the blade 14 is near the rotor 12 and the active part 142 is far from the rotor 12, but not limited by this disclosed embodiment. For example, the passive part 141 can be very far from the rotor 12, or can be substantially placed at the middle of the blade 14. In this embodiment, the feeder 2 placed near the inlet 18 of the axial fan 1 corresponds to the passive parts 141, so that the main airflow from the feeder 12 can drive the blades 14 rotating around the shaft 13.

As the main airflow from the feeder 2 impacts on the passive parts 141, the rotor 12 and the blades 14 rotate around the shaft 13, generating the pressure difference by the active parts 142 of the blades 14 to impel the airflow. According to the law of conservation of energy, it is understood that the product of the volume of airflow per unit time Q and the pressure P of the inlet 18 is equal to that of the outlet 19. Thus, the feeder 2 can provide a high-pressure airflow to blow on the passive parts 141 of the blades 14 rotating around the shaft 13. With the conversion of the axial fan 1, the exterior airflow can be drawn into the axial fan 1 to increase flow rate of the airflow of the outlet 19 and to decrease the pressure at the outlet 19, so that the low-pressure airflow from the outlet 19 blows on, but does not damage, the delicate heat source while dissipating heat therefrom.

In FIG. 4, an axial fan 1′ of the second embodiment differs from the axial fan 1 in that a first partition 143 is disposed between the passive parts 141 and the active parts 142, i.e., the passive part 141 and the active part 142 is separated by the first partition 143, to reduce airflow interference between the passive parts 141 and the active parts 142. The first partition 143 can be a complete circular ring or hollow cylinder disposed on the blade 14 and between the passive parts 141 and the active parts 142, or the first partition 143 can be formed by a plurality of segmented circular portion rings disposed on the blade 14 between the passive parts 141 and the corresponding active parts 142, respectively.

When the airflow from the feeder 2 impacts the passive parts 141 of the blades 14, airflow field (along arrows b2) around the active parts 142 is separated from airflow field (along arrows a2) around the passive parts 141 by the first partition 143, to increase the flow rate of airflow.

A second partition 150 corresponding to the first partition 143 can be further provided on the rib 15. The second partition 150 can be a complete circular ring or hollow cylinder, or formed by a plurality of segmented circular portions rings to separate the airflow passing though the passive parts 141 from that of the active parts 142. Thus, interference and disturbance can be effectively reduced, to increase the efficiency of the axial fan 1′.

While the invention has been described with respect to preferred embodiment, it is to be understood that the invention is not limited thereto, but, on the contrary, is intended to accommodate various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 

1. A fan, comprising: a base; a rotor mounted on the base; and at least one blade disposed around the rotor and comprising a passive part corresponding to an external feeding port, and an active part so that a main airflow from the feeding port drives the passive part to rotate so as to synchronously rotate the active part.
 2. The fan as claimed in claim 1, wherein the passive part is near the rotor and the active part is far from the rotor.
 3. The fan as claimed in claim 1, wherein the main airflow is divided into a first airflow and a second airflow by the passive part so that a pressure difference formed between the first and second airflows drives the passive part to rotate.
 4. The fan as claimed in claim 3, wherein the passive part comprises a wing section.
 5. The fan as claimed in claim 1 further comprising an inlet and an outlet, wherein the pressure at the outlet is smaller than that at the inlet when the active part rotates.
 6. The fan as claimed in claim 1, wherein the blade further comprises a first partition and disposed between the passive part and the active part.
 7. The fan as claimed in claim 6, wherein the first partition is a circular ring or a hollow cylinder.
 8. The fan as claimed in claim 1 further comprising a housing and a rib positioned between the housing and the base.
 9. The fan as claimed in claim 8 further comprising a second partition disposed on the rib.
 10. The fan as claimed in claim 9, wherein the second partition is a circular ring or a hollow cylinder.
 11. A fan without a motor, comprising: a base; a rotor mounted on the base; and at least one blade disposed around the rotor and comprising a passive part corresponding to an external feeding port, and an active part, wherein a main airflow from the feeding port functions as a source of power for driving the passive part so as to synchronously rotate the active part.
 12. The fan as claimed in claim 11, wherein the passive part is near the rotor and the active part is far from the rotor.
 13. The fan as claimed in claim 11, wherein the main airflow from the feeding port is divided into a first airflow and a second airflow by the passive part so that a pressure difference formed between the first and second airflows drives the passive part to rotate.
 14. The fan as claimed in claim 13, wherein the passive part comprises a wing section.
 15. The fan as claimed in claim 11 further comprising an inlet and an outlet, wherein the pressure at the outlet is smaller than that at the inlet when the active part rotates.
 16. The fan as claimed in claim 11, wherein the blade further comprises a first partition and disposed between the passive part and the active part.
 17. The fan as claimed in claim 16, wherein the first partition is a circular ring or a hollow cylinder.
 18. The fan as claimed in claim 16, wherein the first partition comprising a hollow cylinder disposed between the passive part and the active part.
 19. The fan as claimed in claim 11 further comprising a rib and a housing, wherein the rib portion is mounted between the housing and the base.
 20. The fan as claimed in claim 19 further comprising a second partition disposed on the rib.
 21. The fan as claimed in claim 20, wherein the second partition is a circular ring or a hollow cylinder. 